Recent progress in advanced medical therapies is focused on single cell level resolution. Such technologies hold promise to reduce off-target effects by directing therapeutic agents exclusively to localized diseased tissue. Several factors are important for the cell-targeted therapies among which prevention of premature release of the toxic remedies is one of the most important ones. Several drug delivery systems activated by heat, magnetic fields, ultrasound, or light are being explored. The other attractive approach to localized therapies is the use of molecules that are produced by the disease itself as a trigger activating the therapy.
New therapies for cancer treatment are focused on targeted drug delivery of a therapeutic to a target site where cancer cells are located within the body of a patient. For example, many naturally derived, recombinant or synthetic ligands (e.g., antibodies, antibody fragments, aptamers, etc.) can specifically bind to corresponding antigens expressed on a surface (i.e., a cell membrane) of specific cancer cells. However, conventional drugs have numerous side effects which can still be present in spite of targeted drug delivery. Other approaches have used carriers that rely on pH change across the liposome bilayer or pathophysiological abnormalities of vascular system in the cancerous tissues (EPR effect) to passively accumulate and retain the drug in the vicinity of diseased targets.